We are requesting funds in partial support of the new Gordon Research Conference on Cellular Osmoregulation: Sensors, Transducers and Regulators (August 10-15, 2003, Bristol, RI). These funds will be used to pay registration, accommodation and travel expenses for invited conference participants (including junior scientists selected on the basis of submitted abstracts) as well as 20 additional investigators selected for the excellence of their science and to foster human diversity. This conference will provide a forum for analysis of osmoregulatory mechanisms by biophysicists, biochemists, molecular biologists, microbiologists, cell biologists and physiologists. Fluctuations in extraceltular osmolality elicit transmembrane water and solute fluxes that profoundly perturb cell structure, cytoplasmic composition and cell function. Sensors, transducers and regulators ameliorate the consequences of those perturbations by modulating the accumulation and release of selected solutes. The identification of osmoregulatory genes and enzymes in diverse organisms has raised important new questions that can be answered only through interdisciplinary cooperation. How are osmotic shifts sensed? How do macromolecule-water-solute interactions modulate macromolecular structure, assembly and function? Which consequences of osmotic shifts are most critical to cell function? What governs the selection of cytoplasmic solutes and why do solutes vary in their impact on cell structure and function? Explanations of water-solute-macromolecule-solid matrix interactions provided by biophysicists and biochemists will offer new perspectives and tools to biologists who study cellular osmoregulation. In return, descriptions of osmoregulatory adjustments to the cytoplasmic solute complement in vivo will provide a physiological context for investigations of the interplay between solution environment and macromolecular structure/function, raising new questions. The roster of discussion leaders and speakers invited to participate in this conference will include senior scientists who are established leaders in their fields as welt as junior scientists who have recently contributed exciting data. Time slots will be reserved for the inclusion of late-breaking developments. Its inter-disciplinary focus renders this conference relevant to the missions of several Institutes including NIDDK and NIGMS. Assignment to NIDDK is proposed since it supports prominent conference participants who study mechanisms that allow kidney cells to thrive despite the fluctuating osmolality, salinity and urea concentration associated with the renal concentrating mechanism